TheL5 group (shown in green) and theL4 group (light blue) ofMars andJupitertrojan asteroids shown along with the orbits of Jupiter and the inner planets. Mars is shown in red. The outer orbit is that of Jupiter.Animation of 1999 UJ7 relative to Sun and Mars 1600-2500 Sun· 1999 UJ7· MarsAnimation of 2007 NS2 relative to Sun and Mars 1600-2500 Sun· 2007 NS2· Mars
TheMars trojans are a group oftrojan objects that share theorbit of theplanetMars around theSun. They can be found around the twoLagrangian points 60° ahead of and behind Mars. The origin of the Mars trojans is not well understood. One theory suggests that they were primordial objects left over from the formation of Mars that were captured in its Lagrangian points as theSolar System was forming. However, spectral studies of the Mars trojans indicate this may not be the case.[1][2] Another explanation involves asteroids chaotically wandering into theMars Lagrangian points later in the Solar System's formation. This is also questionable considering the short dynamical lifetimes of these objects.[3][4] The spectra of Eureka and two other Mars trojans indicates anolivine-rich composition.[5] Since olivine-rich objects are rare in the asteroid belt it has been suggested that some of the Mars trojans are captured debris from a large orbit-altering impact on Mars when it encountered a planetary embryo.[6][3]
Presently, this group contains 17 asteroids confirmed to be stable Mars trojans by long-term numerical simulations but only nine of them are accepted by theMinor Planet Center.[7][3][4][8][9][10][11]
Due to close orbital similarities, most of the smaller members of the L5 group are hypothesized to be fragments ofEureka that were detached after theYORP effect accelerated Eureka's rotational period to the present 2.69 hours. The L4 trojan1999 UJ7 has a much longer rotational period of ~50 h, apparently due to a chaotic rotation that prevents YORP spinup.[12] The spectrum of 121514 show a certain resemblance to that of 2023 FW14 and a common origin cannot be discarded.[13] The spectra of 121514 and 2023 FW14 are very different from those of the Eureka asteroid family members.
